324 THE MIcRoscoPE 
dition an abundant filamentous growth throve upon the surface 
of the fluid. One per cent. of the carbolic acid did not instantly 
kill the yeast, many cells of which had started and put forth 
from one to three or four generations of buds, but the cells were 
small. There was no film of other fungus on the surface as in 
most of the weaker strengths, and the fluid was clear. The 
appearance made the conclusion almost necessary, that the yeast 
had started to grow but was overcome by the carbolic acid. This 
was a surprise, and shows that the reputed antiseptic power of 
the reagent is exaggerated. 
2. The corrosive sublimate is a far more powerful aniieanee 
for while yeast throve in the presence of J, per cent. of it, it 
was greatly checked in the presence of ,4, per cent. if not en- 
tirely killed, and it was killed at once by , per cent. 
3. Acetic acid up to nearly one per cent. is not unfavorable, 
and the few tests seemed to indicate that it was actually con- 
ducive to the growth of yeast. One per cent., and ten per cent. 
and even twenty per cent. do not instantly kill, but all decidedly 
hinder growth by budding and the development of the indi- 
vidual cells, the latter looking shrivelled and small, instead of 
large and translucent. The class did not study the individual 
cells very particularly, but I may say that in several of the fluids 
which did not kill at once, the cells began to bud but did not 
attain the size of fine healthy cells, and the cells’ contents were 
affected so that they were not translucent as in normal yeasts, 
but more as if wrinkled or shrivelled; in dead yeasts the cell 
wall becomes empty save for the presence of a few dancing, 
highly refractive droplets. 
4, Hydrochloric acid of yo per cent. was found to retard the 
yeast in no degree, but one per cent., and ten per cent. were both 
deleterious, judging from the scanty growth and few buds as 
well as the shrivelled cells, but not fatal at once, possibly not in 
- ten days. 
5. In sulphuric acid of one per cent., the strongest tried, yeasts 
were thriving finely, better than in acetic acid of the same 
strength. The sulphuric acid is therefore less harmful than 
hydrochloric though one might imagine that the reverse would 
be the case. 
6. Alcohol in amount up to one per cent. was innocuous, and 
in ten per cent. the cells were alive and budding, thottgh the 
